Yup, it may refer to the same issue which you have pointed out. But, why the compiler deduce the return type in a inconsistent way, where it can correctly deduce the return type in a single simple statement, whereas it fails in another way? Thanks. On Fri, Dec 5, 2014 at 11:19 PM, Jonathan Wakely <jwakely.gcc@xxxxxxxxx> wrote: > On 5 December 2014 at 02:31, Yu Sheng Oh wrote: >> HI, >> >> I have a piece of code at http://goo.gl/r2ySE6 >> >> Refer to the code, with option of "-O2 -std=c++1y", when we comment >> out the statement "id<int>;" clang-3.4.1 compiles the code >> successfully, but g++-4.9.0 compiles failed, where g++ complains that >> "unresolved overloaded function type", which in turn implies that at >> the point of calling compose function, id<int> is not instantiated. > > It does seem to be a bug, but I don't think the problem is that the > function isn't instantiated. > > I think the compiler is failing to deduce the return type of id<int>, > because it works if you change it to not use "auto" as the return > type. > > I've reported it to Bugzilla as > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59912 with a simpler > example, thanks for reporting it to us.
